1. Field of the Invention
The present invention relates to a technique for liquid-processing a substrate surface, particularly to a technique for removing a film laminated on the substrate surface.
2. Description of Related Art
In recent years, a wiring connecting device has been further miniaturized in accordance with high integration of a semiconductor device. Thus, a technique, which has been conventionally used for mainly forming a device such as a gate electrode, is applied to a wiring process (BEOL (Back-End-of Line) process). For example, when a via hole is etched in an interlayer dielectric film, the interlayer dielectric film is sometimes coated with an antireflection film for preventing influence caused by a reflected light upon exposure. In addition, there is sometimes formed a mask layer for compensating a thickness of a resist film which is thinned to cope with the miniaturization of a wiring. In this manner, a multiple of films are formed on the film to be patterned (for example, JP2001-15479A).
On the other hand, a so-called low-k material has been employed as a material for an interlayer dielectric film to be etched. The low-k film has a dielectric constant lower than that of conventional SiO2, in order to prevent increase in capacity between wirings in accordance with miniaturization of wirings. A porous material such as SiOCH is used as such a low-k material. As compared with SiO2, the low-k film has lower plasma resistance and lower chemical resistance. Thus, when an antireflection film is removed by a conventional method such as an ashing method using an oxygen plasma, or a releasing method using an SPM (Sulfuric acid-hydrogen Peroxide Mixture) liquid, there is a possibility that the interlayer dielectric film made of the low-k material might be also damaged. Thus, there is required a new removal method that does not damage a basic pattern (low-k material).
As one of the removal methods that does not have a great influence on the low-k material, it is under review to use a chemical liquid in which an amine-based release agent, which has a release performance smaller than that of a conventionally used SPM liquid, is dissolved in an organic solvent. However, since such a chemical liquid may lack ability to dissolve an antireflection film, it can be expected that the method using such a chemical liquid takes more time as compared with the ashing method and the SPM method, to thereby deteriorate a throughput of an apparatus.